The present disclosure relates to a battery including an anode having a coating.
In recent years, portable electronic devices such as notebook-sized personal computers, combination cameras, and mobile phones have been introduced one after another, and their size and weight have been reduced. Accordingly, secondary batteries have been highlighted as a portable power source, and researches to obtain a higher energy density have been actively conducted. In such circumstances, as a secondary battery having a high energy density, lithium ion secondary batteries have been proposed and in practical use.
In the past, in the lithium ion secondary batteries, an electrolytic solution which is a liquid electrolyte in which a lithium salt is dissolved in a nonaqueous solvent has been used as a substance working for ion conduction. Therefore, to prevent leakage, it has been necessary to use a metal container as a package member and strictly secure the airtightness of the inside of the battery. However, when the metal container is used as a package member, it has been extremely difficult to form a thin sheet type battery with the large area, a thin card type battery with a small area, a flexible battery in the shape having a higher degree of freedom or the like.
Therefore, instead of the electrolytic solution, secondary batteries using a gelatinous electrolyte in which an electrolytic solution is held by a polymer have been proposed (for example, refer to Japanese Unexamined Patent Application Publication No. 2001-283910). Such a battery is free from the leakage. Therefore, a laminated film or the like can be used as a package member. Thus, its size, weight, and thickness can be more reduced. In addition, the degree of freedom of the shape can be increased.
However, when the laminated film is used as a package member, there is a disadvantage as follows. That is, when the battery is stored in a high temperature environment, the battery is easily swollen due to gas caused by decomposition of the electrolytic solution. Therefore, it is desirable to provide a battery capable of preventing swelling.